<!DOCTYPE html>
<title>Moving fullscreen document's body into a fullscreen iframe</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../trusted-click.js"></script>
<iframe allowfullscreen></iframe>
<script>
// wait for load event to avoid https://bugzil.la/1493878
window.onload = function() {
  async_test(t => {
    const iframe = document.querySelector('iframe');
    const iframeDoc = iframe.contentDocument;

    // Enter fullscreen for the iframe's body element.
    trusted_request(t, iframeDoc.body, iframeDoc.body);
    document.onfullscreenchange = t.step_func(() => {
      assert_equals(document.fullscreenElement, iframe, "document's initial fullscreen element");
      assert_equals(iframeDoc.fullscreenElement, iframeDoc.body, "iframe's initial fullscreen element");

      // Then, move the outer document's body into the iframe. This is an unusual
      // thing to do, but means that the iframe is removed from its document and
      // should trigger fullscreen exit.
      iframeDoc.documentElement.appendChild(document.body);

      // If we exit in an orderly fashion, that's all one can ask for.
      document.onfullscreenchange = t.step_func_done(() => {
        assert_equals(document.fullscreenElement, null, "document's final fullscreen element");

        // Because the iframe was removed, its browsing context was discarded and
        // its contentDocument has become null. Because that browsing context was
        // neither a descendant browsing context nor had an active document,
        // nothing at all was done with it in the exit fullscreen algorithm, so
        // its fullscreenElement is unchanged.
        assert_equals(iframe.contentDocument, null, "iframe's content document");
        assert_equals(iframeDoc.fullscreenElement, iframeDoc.body, "iframe's final fullscreen element");
      });
    });
  });
};
</script>
